Microwave oven



FIG. 1 is a front elevational view of a microwave oven showing our new design;

FIG. 2 is a right side elevational view thereof;

FIG. 3 is a left side elevational view thereof; and,

FIG. 4 is a top plan view thereof.

The rear portion of the microwave oven not shown in the drawings or described in the specification forms no part of the claimed design. 

The ornamental design for a microwave oven, as shown and described. 